I suppose, like I mentioned, you have to be aware of the potential risks, against some pretty good savings, when buying from AliExpress.
I have been fortunate with the dealers I have bought from, going back to just over a decade when I bought Analogue CCTV stuff from them.
I have saved a comparative fortune over the years against the prices in the UK. I do remember one of the dealers I bought from sold me a replacement lens kit, when I changed an analogue camera from 6mm to either 2.8 or 4mm. That kit was very cheap and the contact and service was great.
Neither myself or my friend has had issues with either cameras, DVR's or, later, NVR's when bought from them.
The earlier stuff seemed to be hacked Chinese kit, hacked to the English language. There were ways of upgrading the firmware, long forgotten, but there were very real risks as well.
The two Hikvision cameras I recently bought from them are Internal based and both have been updated to the recently released firmware with no issues.
Always going to be risks, real or not. But offsetting that is the potential to make some damn good savings over what can be charged here.
EDIT: Thinking about it, a little vague tho as it was a long time ago. I did have some issues with one analogue camera many years ago, that was several months after buying it. I sent details etc to the seller, including video of the problem with the image, they sent me a brand new replacement camera. Again a little hazy on the details, but it worked out well in the end.